Magnesium-zinc ceramic ferrite containing copper



Patented Feb. 23, 1954 fi -70,331 MAGNES IUM ZI=NC CERAMIG manna GONIAINING GOPP-ER Ernst Aware-Schoenberg, Metuclien; 3;, as-

signqr to Stewfiite=Research Corpdratiom Kea 's lie'y, Nt'J acoifporatidn of Delaware-- No Dif au ingr Application September 28, 1951, Serial No. 248,389

invention relates to-"a magnetically strong" ferromagnetic ceramic material consisting pri marily' of them'agne'sium zine type of ferrite;

The ferrites" comprise a group-=of"crysta1-time com ounds of the general formula X('M'0'*)- eral bivalent metal oxides and which isapproximately '-1":l. Most of these compounds have '3; 'spinel structure an'd ferromagnetic prop erties.; When M'"""'6 is ferrousoxiiie the' ferrite isc'alled magnetite (FesOb Mo-stoftheierrites which have a high-'perme'ability"'containan es meability properties without the addition ofany great'amountof nickel oxide;

One way-of avoiding the use or nickel is its replauenrentbymanganese. Manganese-Emma rites" (smeaexcellent properties. But these bodies have"t'o"be"fired in a strictly controlled neutral atmosphere, a procedure not quite easy to carryout especially when large quantities-of magnetic cores have to be handled. Manganese, orrtheother hand, is not'too plentifuleither.

The "fierrites made from the tivalem 'oxidesbf magnesium and" zinc offer" the advantage that these materials "are'easi'ly availableand that "the" magnesimn-zinc f errites do not require firing: aprotective atmosphere, i. e, no special;precautions need to-be takentc include protective gases nor to exclude atmospheric air 'dining'the firing; cooling or other'heat treatment ofthe's'e' ferrites; However, there is a disadvantage too: the magnesiuin zii'i'c' f'erri'tes' a'r'e magnetically not very strong.

This invention is based o'nfthe discovery that the permeability andother magnetic properties of thermagnesium-zinc ferrites can be consider ably improved by-the addition of 'a small amount of cupric'oxide withoutidestroying the otheradvantages of the magnesium-zinc ferritesi'.

An object of the invention therefore is to provide a magnesium-zinc type of ferrite with strong magnetic: prop erties.

Another chjectcf the invention is to-provide a term-magnetic magnesium zinc ferrite with strong magnetic properties that can be fired and otherwise treated without a protective atmosphere.

These objects and others ancillary thereto are obtained by adding a small proportion of cupric oxide to a ferrite in which the bivalent oxides are primarily magnesium and zinc oxides.

Nickel oxide is expensive" The copper oxide (CuO) is added in the proportionof it-87% by weight, preterably in; the preparation: of '2 -to -5%- :by weights 7 The copper oxide. (CuO) may be addedassuchi to: the-raw composition-but aivenysatisfiactory way of. addin it-is thertorm -of thebasic-copper carbonate The incorporation; 0t smallamounts oX-ide-whichmay be added-in the formiof lithium carbonate facilitates the reaction and improves themagneticpropentiesr H Thiamine and magnes'ium oxides may be added; in approximately equal; molar" proportions. but this is-not necessary asthe-molmroportion oii ZnQ: MgO-may vary scmewihat 'trom iize toL44a3.

' The totall -mol{.preportion. of, the when oxides is.- approximately equal! to the! moi proportion F6293. but can vary- :fromto 1-: 1.1.. Thain.- vention,}both: as toits organization and itsmethot ofoperation, together with additional objects and: advantages thereof will bestnbe understood; from the -following.--descniption of specific embodiments when read. iniconnection with the, ac.- companying examples;

-Aa mixconsistingz of -8 weight percentot MgQ- -lia weight :per cent of: :ZnQ and; 7.4: weight per cent :of FeaQgais wet-ballmilledsfor .-15.-.hours then dried and ipu lveni'zeda A tter adding 0f water ring. samples-z aregpressed which: :are': subjected to the firing at- 24%" under the free access. ofain. The-magneticpropertiesmeasured are found in the :tollewing table minder :mix. consisting-v sot 75 weight per cent of MgO, 16.5 weight-:pereentofzna ,73-weig ht1per centof F6201 and-Sweight per cent of basic copper carbonate ocurionoazoucoaa waswet ball milled; for 15 hours, then dried; and pulverized; After adding 6% of water ring samples; were pressed, which were subjected to the same firing as described in Exar'hpleTR. The magnetic properties measured are found in the followingzitable underBz:

' it B o,minalipimmettintysm 360 Y 425 #mwma-vimupimenneabili q; "1,2660 B' ssitur'atfon flixx'd'ensity (gauss); 900

EXAMPLE 2 C. A mix consisting of 7 weight per cent of MgO, 3.5% of lithium carbonate, LizCOa, 17% of ZnO and 72% of F6203 was wet ballmilled for 15 hours, dried and pulverized. After adding 6% (Cu (OH) 2.2CUCO3) and 71% of F6203 was wet-ballmilled for hours, then dried and pulverized. After adding 6% of water, ring samples were pressed and subjected to the same firing as described in Example 2C. The magnetic properties measured are found in the following table under D.

an, initial permeability 425 590 m maximum permeability l, 350 2, 450 13,, saturation flux density 3, 000 3, 020

The second example differs from the first inasmuch as there is some lithium oxide present as an ingredient of the body. Lithium oxide facilitates the reaction of the bivalent oxides and iron oxide, forming a ferrite itself. But although the lithium oxide content of 2D is smaller than that of 2C, 2D proves the stronger material due to the addition of the copper compound.

Bodies featuring these properties are especially valuable for the use as inductance and transformer cores in the lower hand of high frequencies as between about 10 and 100 kilocycles.

The described method of adding copper is not limited to pure magnesium-zinc-ferrites. In cases where the use of nickel oxide is not objectionable a magnesium-nickel-zinc-copper-ferrite is very satisfactory. It goes without saying, that the magnetic performance of a nickel containing body is superior to that of a nickel free one. The copper addition, however, offers considerable help raising the qualities of a nickelfree magnesium-zinc ferrite up to a standard where its usefulness for many technical purposes is granted. The improvement effect of the copper addition is always noted: in nickel-zinc ferrites, magnesium-zinc ferrites and magnesiumnickel-zinc ferrites. In my application Serial No. 189,056, filed October 7, 1950, disclosing a nickel- Zinc ferrite, an addition of 1.254%, by weight of copper oxide is employed. For the magnesium zinc ferrites the proportion of copper oxide should be from 1.5 to 8% by weight of the ferrite composition, preferably between 2 and 5%. With respect to the higher percentages of copper oxide (5 to 8%), the bodies described probably should not be looked at as magnesium-zinc ferrites with some copper oxide added as a kind of catalyst, but rather as triple ferrites of the system I claim:

1. A ferromagnetic body of high permeability properties consisting primarily of the components ZnO, MgO and Fezoa the ratio of the total mol proportion of ZnO and MgO to F8203 being between l:.9 and 1:1.1, the mol proportion of ZnO:MgO being from 3:4 to 4:3 and containing in addition from 1.5 to 8% by weight of copper 4 oxide, and from 0 to 2% by weight of lithium oxide.

2. A ferromagnetic body of high permeability properties consisting primarily of the components ZnO, MgO and F8203 the ratio of the total mol proportion of ZnO and MgO to FezOa being between 1:.9 and 1:1.1, the mol proportion of ZnO:MgO being from 3:4 to 4:3 and containing in addition from 1.5 to 8% by weight of copper oxide.

3. A ferromagnetic body of high permeability properties consisting primarily of the components ZnO, MgO and F8203 the ratio of the total mol proportion of ZnO and MgO to FezOa being between 1:.9 and 1:1.1, the mol proportion of ZnOzMgO being from 3:4 to 4:3 and containing in addition from 1.5 to 8% by weight of copper oxide and from .2 to 2% by weight of lithium oxide.

4. A process of making a ferromagnetic mixed ferrite consisting primarily of the components ZnO, MgO and R203 the ratio of the total mol proportion of ZnO and MgO to F8203 being between 1:.9 and 1:1.1, the mol proportion of ZnOzMgO being from 3:4 to 4:3 comprisin the steps of mixing the metal oxides in the required proportions, adding a cu-pric oxide producing ingredient in amounts to give a cupric oxide content of 1.5 to 8% by weight of the composition, forming the composition to shape and firing the shaped product under free access of air without providing a protective atmosphere.

5. A process of makin a ferromagnetic mixed ferrite consisting primarily of the components ZnO, MgO and F8203 the ratio of the total mol proportion of ZnO and MgO to F6203 being between 1:.9 and 1:1.1, the mol proportion of ZnOzMgO being from 3:4 to 4:3 comprising the steps of mixing the metal oxides in the required proportions, adding basic copper carbonate in amounts to give a cupric oxide content of 1.5 to 8% by weight of the composition, thereafter molding and. firing the composition under free access of air without providing a protective atmosphere.

6. A ferromagnetic ceramic core for inductances and transformers especially suitable for the frequency band of 10 to kilocycles consisting of a triple ferrite of the oxide system MgOZnOCuOFezO3, the mol proportion of bivalent magnesium and zinc oxides to ferric oxide being from 1 .9 to 1 1.1, the amount of copper oxide being from 1.5 to 8% by weight of the composition and the mol proportion of ZnOzMgO being from 3:4 to 4:3.

ERNST AIBERS-SCHOENBERG.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,565,058 Albers-Schoenberg Aug. 21, 1951 2,565,111 Albers-Schoenberg Aug. 21, 1951 2,565,861 Leverenz et al. Aug. 28, 1951 OTHER REFERENCES New Developments in Ferromagnetic Materials, Snoek (1947), Elsevier'Pub. '00., Inc., page 69. 

1. A FERROMAGNETIC BODY OF HIGH PERMEABILITY PROPERTIES CONSISTING PRIMARILY OF THE COMPONENTS ZNO, MGO AND FE2O3 THE RATIO OF THE TOTAL MOL PROPORTION OF ZNO AND MGO TO FE2O3 BEING BETWEEN 1:9 AND 1:1.1, THE MOL PROPORTION OF ZNO:MGO BEING FROM 3:4 TO 4:3 AND CONTAINING IN ADDITION FROM 1.5 TO 8, BY WEIGHT OF COPPER OXIDE, AND FROM 0 TO 2% BY WEIGHT OF LITHIUM OXIDE. 